A cleaning sheet which is prepared by impregnating, for example, a nonwoven fabric with a surfactant which is used in a foamed state by the addition of water has been known in the art (Patent Document 1, Patent Document 2, and Patent Document 3). It is required for the sheet to have a moderate strength and soft feeling to the touch because the sheet is used to clean the skin by massaging the skin. It is also required for the cleaning liquid which contains a surfactant to be less irritant and to have a good foamability. However, there is the case where conventional cleaning sheets damage the skin when the skin is rubbed excessively while cleansing and these cleaning sheets are therefore unsatisfactory.
These cleaning sheets are preserved in the condition that these sheets are stacked on each other and packaged in a tightly sealed state. However, there is, for example, such a problem that the sheets stick together and foam up when they are taken out. Such problems concerning the appearance or convenience of products give a very unfavorable impression to consumers, which is undesirable.
Also generally an aqueous liquid containing a surfactant in a high concentration is highly viscous and it is therefore difficult to impregnate the sheet efficiently in the production process.
Patent Document 4 describes a wet fiber sheet impregnated with a cleansing composition having a pH of 3 to 6 and containing ethanol in a specified amount. However, this fiber sheet uses a combination of ethanol benzoic acid and paraoxybenzoates for mildew-proofing. This fiber sheet is used for wiping applications such as wet tissues, and thus it is not intended to be used in a foamed state.    [Patent Document 1] JP-A-2003-27094    [Patent Document 2] JP-A-2002-363063    [Patent Document 3] JP-A-2003-95861    [Patent Document 4] JP-A-11-99088